It has come to our attention that some veterinary surgeons
and keepers are relying upon data provided by the 'Jackson Ratio' graph
in circumstances which are not appropriate.

The 'Jackson Ratio' graph may only be used with tortoises of
'average' body morphology, e.g. Testudo graeca and Testudo hermanni. This
graph MUST
NOT be used with Testudo horsfieldii or Testudo marginata, as it
will invariably produce incorrect results. The body shape of these
species is such that T. horsfieldii, being
'short and square' will tend to read 'overweight' even if it is
actually underweight. T. marginata, being
'long and narrow' will, on the other hand, read 'underweight' even if
it is of a perfectly average and safe weight for its size.

We
also take this opportunity to point out that the 'Jackson Ratio' graph
is of no use whatsoever for assessing the health of Hinge-back,
Leopard, Sulcata or any other tropical, non-hibernating species.
Neither is it of value in determining the suitability of Box turtles to
hibernate.

This graph must ONLY be
applied to Testudo
graeca and Testudo hermanni and to
no other species. When measuring for the Jackson Ratio graph, use the
straight line carapace method, and do not measure 'over the curve'.